The present invention relates to a windshield wiper arm fixing device, in particular for windshields of automotive vehicles.
The importance of reliable and correct fixing of such equipment to the performance of the windshield wipers and therefore to safe driving of the vehicle in rainy or snowy weather is well known. In the devices most widely used at present, the ends of the oscillating spindles to which the windshield wiper arms are fixed have a screwthreaded part onto which is screwed a nut for locking the arm, the screwthreaded part, which is of smaller diameter than the oscillating spindle, being joined to the latter by a generally frustoconical bearing surface with regular splines along the generatrices of the frustum of the cone.
Existing arms have a corresponding frustoconical mounting hole which, when first fitted, is forced over the splined part of the spindle, whose splines are then imprinted into the bore of the arm, which is generally made of a metal softer than the steel of the spindle, such as a zinc-based alloy known as Zamak or an aluminum-based alloy.
The imprinting of the splines in the bore prevents the shaft rotating relative to the spindle. However, this type of assembly, although simple and inexpensive, is not very resistant to demounting and does not guarantee that the arm is perpendicular to its rotation axis, in particular where it is nested over the splined frustoconical part.
If an adjustment in its position proves necessary, clamping it again in a different angular position on the surface of the bore of the arm, which already has splines imprinted in it, will take place on top of the original splines, causing them to be chewed up, and the splines will no longer be able to transmit the drive torque for the windshield wiper arm. For this reason, automotive vehicle manufacturers scrap any windshield wiper arm that is mounted incorrectly, either on the production line or as a repair, and replace it with a new one in order to guarantee mechanical strength and to avoid a reduced locking effect and risks of deformation on the clamping surfaces that can lead to defective positioning of the arm. The quality of the assembly will depend on the care with which the arm was initially positioned on the production line.
This type of mounting on a splined frustoconical bearing surface does not accurately control the axial hi position of the arm on the spindle because, although the nature of the materials used enables the male splines on the steel spindle to be impressed into the female cone of the frustoconical bearing surface, the frustoconical shape adopted makes it difficult to maintain the assembly tension (the materials used, which are generally soft metals, having a tendency to creep), degrading the quality of the connection, and the shaft then turns within the female frustoconical bearing surface without driving the windshield wiper.
On the other hand, if the frustoconical assembly is well designed and functions correctly, it is inherently self-wedging and an extractor is required to demount it.
Moreover, with a frustoconical bearing surface, especially a short one, it is difficult to guarantee that the arm is perpendicular to its spindle. Any such defect of perpendicularity leads to malfunctions and in particular to serious variations in the intended wiping speed and to noise and vibration of the rubber windshield wiper blade.
Pressed sheet metal arm drivers give rise to other problems. Being made of steel, the marking of the frustoconical bearing surface of the driver by the splines on the spindle will be very superficial, because of the hardness of the material and the particularly small height of the bearing surface, and this will necessitate significantly increasing the assembly pressures
The subject matter of the present invention is a windshield wiper arm structure which enables precise adjustment of its angular position, combined with low cost, and which can be mounted quickly, in a single operation, with easy adjustment of the angular location of the windshield wiper arm.
According to the invention, a device for fixing a windshield wiper arm hub to the spindle with locking means for locking the arm to the spindle, a cavity formed in the hub containing means for adjusting the angular position of the arm relative to the spindle, said hub bearing on an abutment base nested over a bearing surface of the spindle, is characterized in that, the locking means being adapted to assume either a clamping position or an unclamping position, said adjustment means include a connecting ring constrained to rotate with the spindle and accommodated in said cavity of the hub with some play allowing limited relative angular movement between the connecting ring and the hub in the unclamping position of the locking means, whereas all relative movement between the connecting ring and the hub is prohibited in the clamping position of the locking means.
Advantageously, said angular play of the connecting ring inside the cavity of the hub is determined by nesting of the connecting ring along a polygonal contour.
Accordingly, the contour of the connecting ring can be integrated with the shaft to nest it directly in the complementary cavity of the hub, and the same spring means can be disposed between the shaft and the hub, which eliminates the use of a connecting ring without excessively complicating the shape of the end of the arm. A bearing surface of polygonal shape, for example hexagonal shape, will be formed directly on the shaft, that bearing surface being nested inside a corresponding cavity of the hub having the same, but slightly larger, shape to enable angular play of the arm on the shaft.
Preferably, an angular movement buffering spring member is disposed in a space between the inside of the hub and the outside of the connecting ring.
In this variant, to damp end of sweep impacts on each reversal of the direction of operation, there is provided in the space directly separating the shaft from the hub a buffer member such as a leaf spring of appropriate shape that will equally make it possible to retain the arm in its theoretical adjustment position relative to the shaft.
Advantageously, the connecting ring has a cylindrical outside contour nested inside a corresponding bore of the hub, its rotation in said bore being angularly limited by at least one radial rib able to oscillate in at least one corresponding radial housing of the hub, spring means being disposed between the radial walls of the rib and the facing radial walls of the radial housing.
In a preferred embodiment the connecting ring will have a cylindrical outside contour nested inside a corresponding bore of the hub, its rotation in that bore being angularly limited by at least one radial rib able to oscillate in a corresponding, slightly wider groove in the hub, a larger radial rib being disposed in a larger cavity of the hub, for example in the portion thereof extending along the axis of the arm, bearing buffering spring means being disposed between the radial walls of the rib and the facing radial walls of the cavity. These spring means also determine the theoretical angular location on first fitting and retain the ring, thus facilitating fitting the arm to the shaft in its theoretical centered position and holding it in position during assembly.
There will then be provided a controlled range of adjustment of the angular position of the arm, in elastic bearing engagement. Once fitted, the arm will be locked by tightening the assembly nut with the locking washer, as previously.
Preferably, a metal outer shell forms a housing around the hub.
The arm according to the invention has an end for assembly onto the spindle consisting of a composite structure characterized by an external shell, preferably of pressed sheet metal, forming a drive housing of the windshield wiper arm, which housing is open at the bottom, has a hole at the top through which the spindle passes, and receives means for locking the arm onto the spindle such as a nut with a locking washer or an assembly screw, depending on the types of assembly concerned, this housing containing a separate hub, which is made from a molded or cast material, such as a plastics material or Zamak, aluminum, magnesium, etc., is adapted to receive means for adjusting the angular position of the arm, is nested in and fastened to the housing, and has shapes complementary to those of said housing to fasten the hub into the housing and constrain them to rotate together. The hub can equally be fastened to the housing by other means such as molding, pins, crimping, clipping, or riveting.
This composite structure facilitates complex and precise shaping of the hub by molding, combined with sufficient strength, imparted by covering the housing with sheet steel, which acts as a reinforcing band on the hub and its adjustment and assembly mechanisms and provides a particularly rigid connection to the windshield wiper arm, in particular in the case of a long arm.
The simplest shape for this kind of composite hub could be applied in particular to nesting over spindles with splined frustoconical bearing surface, as in the prior art, but whose bore is extended, starting from the larger base of the frustum of the cone or from its toroidal extension, by a guide sleeve nested over the rod of the spindle and guaranteeing a perpendicular assembly. This first application thereby remedies the main defect of assemblies using spindles with splines on a frustoconical bearing surface.
A variant hub will have a frustoconical bearing surface bore whose larger base can be connected to the cylindrical rod of the spindle by a toroidal connecting surface forming a abutment and therefore improving axial location of the nested hub of the arm, which has an initially smooth surface on which the splines of the spindle will be imprinted. This strengthens the adjustment on a frustoconical bearing surface. The smooth frustoconical bearing surface of the hub has at its larger base end a rounded portion whose toroidal surface nests over and abuts against a splined toroidal surface of complementary shape extending the splines of the frustoconical bearing surface of the spindle as far as its outside diameter.
To improve the rotational interlocking of the frustoconical nesting arrangement, instead of being regularly distributed in the usual way, the splines on the frustum of the cone of the shaft could be irregularly or randomly distributed, so that at least some of them nest correctly in some of the splines imprinted on the smooth frustoconical surface of the arm when it was first fitted.
With regularly distributed splines, if the shaft is offset by one half-tooth, for example, relative to the splines imprinted in the arm, the tips of all the teeth on the shaft will face the tips of all the teeth that were imprinted in the hub during first assembly. This cannot occur with irregularly distributed splines because at least some of them will be in the correct position.
Advantageously, the arm is held perpendicular to the spindle by the abutment base, which abuts on a transverse bearing surface of the spindle.
The perpendicularity of the arm will advantageously be controlled by this abutment base, which can be made from a sintered metal, and whose central hole will have a splined surface that nests over the splined bearing surface of the spindle, said base abutting on the bottom of that bearing surface, which ensures its perpendicular and axial position relative to the spindle through a self-locking assembly with no wedging effect, as well as the perpendicularity of the hub, which bears on this abutment base, whose cylindrical surface provided with a shoulder for centering the hub closes the cavity in the hub containing the means for adjusting the angle of the arm.
To prevent creep due to crushing of the hub when it is clamped against the abutment, the flanks of the housing will have a predetermined height relative to the hub and will bear against the abutment base to maintain the required assembly pressure.
For assemblies on spindles with a cylindrical splined bearing surface, the perpendicularity of the arm thereon is controlled by a abutment base, which can be made from a sintered metal, and whose central hole has a splined surface that nests over the splined bearing surface of the spindle, said base abutting against the end of that bearing surface, which ensures its perpendicular and axial position relative to the spindle by a self-locking assembly with no wedging effect, and also the perpendicularity of the hub which bears on this abutment base, whose circular surface provided with its centering shoulder closes the cavity in the hub containing the means for adjusting the angle of the arm.
Preferably, the height of the flanks of the housing relative to the hub is such that they bear against the abutment base.
Advantageously, the shapes of the housing and the hub and the height of the flanks of the housing relative to the hub are such that the bottom and the flanks of the housing bear on the top and the flanks of the hub, respectively, said hub itself bearing on the abutment base, the flanks of the hub being splined.
Preferably, the connecting ring is constrained to rotate with the spindle by means having cooperating or complementary shapes.
Advantageously, said means having cooperating shapes consist of splines.
Preferably, said means having cooperating shapes consist of polygons, advantageously squares.
Advantageously, the means with cooperating shapes are carried directly by the connecting ring and means with cooperating shapes are carried by the spindle.
Preferably, the connecting ring is constrained to rotate with the spindle by the abutment base, the means with cooperating shapes are carried by the abutment base and means with cooperating shapes are carried by the transverse bearing surface of the spindle, complementary means, which are advantageously indexed, being provided for driving of the connecting ring by the abutment base.
Advantageously, the spindle includes a xe2x80x9cpolarizerxe2x80x9d device consisting of gaps left by missing splines and the splines of the connecting ring of the hub include polarizer splines with no gaps between them, the resulting solid members corresponding to the gaps left by the missing splines of the spindle, the abutment base including a full complement of splines.
Preferably,the radial rib has an elastic end portion adapted to bear on a portion of the corresponding wall of the radial housing.
Thus the windshield wiper arm according to the invention will be mounted on the screwthreaded end of its spindle, in a manner that is known in the art, by locking it by means of an appropriate nut and Washer in a hole of the hub at the end of the arm against a bearing abutment base fastened to the spindle, said end hub having on its locking bearing face a housing in which is nested a connecting ring constrained to rotate with the end of the spindle but free to rotate by a small amount and against a resisting spring bearing force, said assembly being characterized in that the connecting ring has at least one flexible radial rib disposed in a corresponding housing of the hub receiving the connecting ring, rotation of the windshield wiper arm relative to its spindle and the connecting ring in elastic bearing engagement being ensured by elastic flexing of said radial rib bearing against the corresponding wall of its housing.
Advantageously, the radial rib can flex elastically because it has a projecting shape at its end which alone bears on the wall of its housing and allows free flexing of the rib in the housing.
Preferably, the radial rib has at least one flexing lug.
Advantageously, the length of the flexing lugs is less than the radial depth of the housing, the base of the rib forming an abutment bearing on a portion of the corresponding wall of the housing limiting angular movement of the arm while it is being adjusted during first fitting or if it is loosened.
Advantageously, there is at least one angular movement abutment rib on the periphery of the connecting ring.
Preferably, the connecting ring is nested in the corresponding cavity of the windshield wiper arm hub with a taper.
Advantageously, the taper of the external contour of the connecting ring and the corresponding walls of the cavity of the hub is at least equal to or greater than the taper of the arm hub enabling its direct extraction from the mold.
Preferably, the locking means include a nut and a locking washer held in position on the external face of the windshield wiper arm hub by a centering bead thereon which is concentric with the exit hole for the screwthreaded end of the spindle.
Advantageously, it consists of a pre-assembled sub-assembly at the end of the windshield wiper arm including, on the one hand, a nut and a locking washer held in position on the external face of the windshield wiper arm hub by a retaining fork having two top teeth bearing on the washer on either side of the nut and two bottom teeth bearing on the abutment base on either side of the hole for fitting it over the spindle, the bottom teeth being connected by a semifrustoconical shape forming a funnel to facilitate guiding the end of the spindle into the hole in the abutment base.
Preferably, the distance from the bearing face of the connecting ring on the abutment base to the entry of the screwthread of the nut is greater than the distance between the entry of the means with complementary shapes carried by the spindle and the top of the screwthread on the shaft, so that the means with complementary shapes of the ring can be engaged over the means with complementary shapes of the spindle before tightening the nut.
Advantageously, the distance from the face of the abutment base bearing on the transverse bearing surface on the spindle to the entry of the screwthread of the nut is greater than the distance between the entry of the means with complementary shapes carried by the spindle and the top of the screwthread on the shaft so that the means with complementary shapes of the abutment base can be engaged over the means with complementary shapes of the spindle before tightening the nut.
The invention also relates to eliminating noise generated by windshield wipers due to their effectiveness varying as a function of the pressure with which they are pressed onto the windshield. The noise can be caused by poorly controlled inclination of the rubber blade relative to the surface of the windshield, to which may be added excessive pressure of the arm bearing spring. The blade then tends to jerk and cause the whole of the arm to vibrate.
The curved shape of the windshield may also vary from one supplier to another, and it can be beneficial to modify the bearing pressure by increasing the tension of the spring, rather than adding a spoiler whose aerodynamic effect would increase that bearing pressure.
According to the invention, this problem will be solved by articulating the abutment base to the spindle so that it can be adjusted, either in terms of its normal position perpendicular to its attachment spindle or offset by a positive or negative angle relative to that position.
Advantageously, the transverse bearing surface on the drive spindle over which the abutment base is nested includes at least two diametrally opposite flats, limited in the lengthwise direction by shoulder surfaces, which are concave and provided with teeth perpendicular to the spindle and parallel to each other, the abutment base being nested over the bearing surface of the spindle with a clearance enabling it to tilt relative to its normal perpendicular position, and having convex toothed bearing surfaces nesting over the concave toothed shoulder surfaces of the drive spindle, the mutual nesting of the teeth of the bearing surfaces maintaining the chosen inclination of the abutment base when it is being first fitted.
Preferably, the shoulder surfaces on the spindle and the bearing surfaces on the abutment base are segments of cylindrical surfaces of a cylinder whose axis intersects the spindle perpendicularly thereto.
Advantageously, the shoulder surfaces on the spindle and the bearing surfaces on the abutment base are sectors of a sphere whose center is on the spindle and form a ball-joint locked by the nesting of the teeth, the 90xc2x0 relative location of which enables longitudinal sliding of the nested teeth for adjusting the relative location of the perpendicular sets of teeth.
Two adjustment solutions can then be envisaged:
The simpler one, in particular during fitting on the production line, consists of adjusting only one factor at a time, either the tension or the inclination of the bearing spring of the rubber wiper blade, which will be obtained with the same spindle, the same abutment and the same adjuster ring, and therefore without modification of the components, by pivoting the orientation of the spindle 90xc2x0 relative to its drive link, as a function of the required adjustment during fitting to the vehicle, by locating the arm by means of two opposed concave and convex toothed bearing surfaces on the abutment and on the spindle.
The second solution will simultaneously make it possible to:
Adjust the bearing pressure.
Adjust the inclination of the rubber blade.
Adjust both at once.
For example, it may be beneficial to impart a positive or negative angle to the rubber blade, retaining the possibility of remaining neutral or increasing or reducing the bearing pressure.
In this case, two sets of concave toothed shoulder surfaces on the spindle and convex toothed bearing surfaces on the abutment base will be used, forming a bearing surface composed of sectors of a spherical dome centered on the spindle and enabling ball-joint type adjustment of the inclination of the abutment base, the double set of mutually nested teeth ensuring that it is retained in the chosen position.
It will be noted that this solution for adjusting the sweep position by adjusting the position of the bearing abutment base is still very simple and inexpensive, the shapes of the bearing surfaces and the teeth being easily obtained on the spindle by cold stamping and on the abutment by cold stamping or sintering.
Preferably, the spindle has four flats which impart a square section on it and over which is nested the abutment base, whose bearing base is inclined and which transmits that inclination to the connecting ring, constrained to rotate with the bearing base of the abutment base by complementary means consisting of four tongues over which it is nested, different angular locations of the connecting ring and therefore of the windshield wiper arm being obtained by modifying the relative location of the abutment base on its nesting square on the spindle by 90xc2x0 or 180xc2x0.
Advantageously, a washer is disposed between the abutment base and the base of the square on the spindle over which it is nested, the washer having on its face bearing on the abutment a concave toothed surface on which a convex toothed surface of the abutment base bears.
The play between the hub and the ring enabling the angular location to be varied by an amount of the order of several degrees, sufficient for adjusting the position of the windshield wiper, can be ensured by nesting the connecting ring in its cavity of the hub with a clearance along a contour that does not allow the ring to rotate in its cavity, such as a polygonal contour limiting the possibility of angular movement. After placing the arm in the required angular position, the stacked hub and housing will be locked in position against the abutment base by tightening the nut and its arm locking washer to the end of the spindle.
The above kind of device will advantageously consist of a pre-assembled sub-assembly at the end of the windshield wiper arm and including, on the one hand, the nut and its locking washer, held in position on the outside face of the housing, for example by locating lugs formed in the sheet metal of the housing or by a washer equipped with lugs provided with retaining claws, facing the exit hole of the screwthread end of the spindle, and, on the other hand, the assembly of the abutment base, connecting ring and locating spring clipped into the corresponding cavity of the hub, in turns fastened to the housing by studs heat-welded into corresponding holes in the sheet metal of the housing. On demounting, the nut, retained by the mounting lugs, will act as an extractor to facilitate demounting the complete sub-assembly without requiring any other tools.
When this arm sub-assembly pre-assembled in this way is fitted to the end of the shaft, the distance from the bearing face of the connecting ring on the abutment base to the entry of the splines on the shaft will advantageously be greater than the distance between the entry of the screwthread of the nut and the top of the screwthread on the shaft, so that the splines of the ring can be engaged over the shaft before tightening the nut. In this way the ring is engaged over the splines of the shaft before the nut abuts on the end of the screwthread on the shaft to retain the arm angularly on the shaft, so that the operative no longer has to hold the arm in position and therefore has both hands free to fit the second arm and adjust and lock both arms simultaneously.
On the assembly line, the operator will only have to fit this sub-assembly over the splined part of the spindle.
Advantageously, the length over which the hub of the windshield wiper arm is nested, including the length over which the combination of the abutment base and the connecting ring is engaged over the spindle, ensures retention of the hub on the spindle and bracing of the hub to press the windshield wiper blade onto the windshield.
Then the operative will only have to place the windshield wiper arm in the required position with one hand and, holding his nut driver in the other hand, tighten the nut to lock the arm in position. This will minimize assembly time and this adjustment will be repeatable subsequently under any circumstances.
To avoid errors in orienting the arm when fitting it as indicated above, a xe2x80x9cpolarizerxe2x80x9d device is provided enabling the hub of the arm to be mounted on the splines of the shaft in only one position. To this end, the shaft has splines missing, leaving gaps, which enables the abutment, with a fill complement of splines, to be fitted in any orientation, which facilitates assembly, although the connecting ring of the hub of the arm includes polarizer splines with no gaps between them, the resulting solid members corresponding to the gaps because of the missing splines on the spindle, as a result of which the connecting ring can be mounted in only one indexing position, the only theoretically required position, from which the orientation of the arm can be finally adjusted at the level of the angular abutments of the connecting ring in their larger cavities provided with spring means formed in the hub of the arm, as previously described.
This embodiment of a windshield wiper arm structure offers secure positioning of the arm on its spindle, including after demounting, and enables a precise angular position adjustment, if necessary, whilst still being of low cost and compatible with existing mounting spindles, on which this arm will be mounted on vehicle assembly lines by a simple and fast assembly operation less dependent on the human factor, with possible easy adjustment of the angular location of the windshield wiper arm.
The elastic flexing of the radial rib will advantageously be procured by providing a projecting shape such as a bead at its end, that alone will bear on the wall of its housing and allow free flexing of the rib in that housing. To combine flexibility for flexing with sufficient mechanical strength, the radial rib will consist of a plurality of parallel flexing lugs having the same flexing flexibility but whose resistances to flexing will be additive. These lugs could be shorter than the rib, whose more solid base will then form an abutment limiting the angular displacement of the arm during its adjustment on fitting. One or more small solid ribs can also be provided on the periphery of the connecting ring, depending on the required strength, providing this angular displacement limiting abutment function. Considerable adaptability of the assembly structure is therefore obtained by appropriately dimensioning the connecting ring and its rib or ribs.
In this kind of configuration the connecting ring must reconcile the requirements of material flexibility, enabling elastic deformation in flexing of the radial rib, and sufficient mechanical strength of the splines in its bore, which have to be nested over the corresponding splines on the spindle. According to another feature of the invention, the nesting of the connecting ring in the corresponding cavity of the hub will include a taper.
In addition to its conventional function of facilitating molding, that taper will have the result, during locking of the arm on the spindle, compressing the connecting ring in its housing, of exerting a component of pressure perpendicular to the spindle resulting in an effect of banding the connecting ring onto the spindle, which significantly reinforces the splined 1 assembly. Moreover, this taper prevents complication of the tooling for pressure casting the arm, by the provision of demountable parts, if the arm has a skewed shape necessitating a mold extraction plane inclined relative to the spindle. Tapering the outside contour of the connecting ring and the corresponding walls of its housing at an angle at least equal to or greater than that inclination will enable direct extraction of the arm from the mold without adding supplementary mobile members in the mold.
Accordingly, by a dimensional adjustment of the connecting ring as a function of the material chosen and operating constraints, fixing the windshield wiper arm according to the invention will enable easy adaptation to all types of windshield wiper, at moderate cost.
Clearly, the invention:
ensures that the windshield wiper is driven securely, even if the clamping is inadequate,
provides an incompressible mounting in which the assembly tension is maintained by compression spring means,
achieves a perfectly perpendicular and precise axial position of the arm on its spindle,
transmits high drive torques and is more rigid than existing arms,
can be demounted without special tools and replaced quickly and securely in the same position without any possibility of error and as many times as may be necessary throughout the service life of the vehicle,
enables the three adjustments provided (sweep, twist, blade pressure) to be modified without demounting any component, including the clamping nut and its washer,
does not necessitate any modification to existing fabrication techniques and improves the method of mounting the windshield wiper arm on the production line,
enables the windshield wiper arm to remain in its theoretical position on the spindle of its own accord, before tightening the nut, so that the operative has his hands free, and
can be mounted interchangeably on the main spindle diameters already in use.